It is well known in the subterranean well drilling and completion art that relatively fine particulate materials may be produced during the production of hydrocarbons from a well that traverses an unconsolidated or loosely consolidated formation. Numerous problems may occur as a result of the production of such particulates. For example, the particulates cause abrasive wear to components within the well, such as joints, chokes, flowlines, tubulars, pumps and valves as well as any components having directional flow changes. In addition, the particulates may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids using surface processing equipment.
One method for preventing the production of such particulate material to the surface is gravel packing the well adjacent the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a sand control screen is lowered into the wellbore on a workstring to a position proximate the desired production interval. A fluid slurry including a liquid carrier and a relatively coarse particulate material, which is typically sized and graded and which is referred to herein as gravel, is then pumped down the workstring and into the well annulus formed between the sand control screen and the perforated well casing or open hole production zone.
The liquid carrier either flows into the formation or returns to the surface by flowing through a wash pipe or both. In either case, the gravel is deposited around the sand control screen to form the gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the fine particulate materials carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of these particulate materials from the formation.
It is sometimes desirable to perform a formation fracturing and propping operation prior to or simultaneously with the gravel packing operation. Hydraulic fracturing of a hydrocarbon formation is sometimes desirable to increase the permeability of the production interval adjacent the wellbore. According to conventional practice, a fracture fluid such as water, oil, oil/water emulsion, gelled water, gelled oil or foam is pumped down the workstring with sufficient pressure to open multiple fractures in the production interval. The fracture fluid may carry a suitable propping agent, such as sand or gravel, which is referred to herein as a proppant, into the fractures for the purpose of holding the fractures open following the fracturing operation.
The fracture fluid must be forced into the formation at a flow rate great enough to fracture the formation allowing the entrained proppant to enter the fractures and prop the formation structures apart, producing channels which will create highly conductive paths reaching out into the production interval, and thereby increasing the reservoir permeability in the fracture region. As such, the success of the fracture operation is dependent upon the ability to inject large volumes of hydraulic fracture fluid into the surrounding formation at a high pressure and at a high flow rate.
For most hydrocarbon formations, a successful fracture and propping operation will require injection flow rates that are much higher than those required for gravel packing. For example, in typical gravel packing, a single pump capable of delivering one to ten barrels per minute may be sufficient. On the other hand, for a successful fracturing operation, three or four large capacity pumps may be required in order to pump at rates higher than the formation fracture gradient which may range up to 60 barrels per minute or more.
It has been found, however, that the high injection flow rates that are associated with fracturing operations and, to a lesser extent, the particulate matter associated with both gravel and fracturing operations cause erosion to the surfaces of downhole components. For example, the surfaces of the cross-over assembly used during these treatment operations are particularly susceptible to erosion. In order to monitor the wear threshold of downhole equipment, erosion detection systems have been utilized that typically include a series of pressure gauges that monitor pressure changes by measuring pressure at a corresponding series of locations. In these existing solutions, a loss in pressure is a possible indication of a failure of an eroded component.
Hence, the existing solutions are reactive schemes that provide only for a possible detection of failed components. Therefore, a need has arisen for a system and method for monitoring erosion and the structural integrity and health of surfaces subject to erosion and wear. A need has also arisen for such a system and method to monitor the early stages of erosion in downhole components, downhole tubulars, flowlines and surface equipment. Further, a need exists for a proactive approach to monitoring erosion that provides for preventative maintenance of equipment, alterations in treatment or production parameters and minimizes the likelihood of failures caused by erosion.